1. Field of the Invention
The present invention relates to controlling an interference amount. More particularly, the present invention relates to a method for controlling uplink transmission power of a wireless communication system, and an apparatus thereof.
2. Description of the Related Art
In a wireless communication system such as a Wireless BROadband (WIBRO) system, data transmission performance deteriorates at a terminal of a serving base station due to interference caused by uplink data from a terminal of a neighboring base station. Particularly, such a problem becomes worse at a terminal located at a cell edge area.
In the case of open-loop power control, a base station broadcasts a Noise and Interference (NI) value measured from a neighboring cell and a terminal increases power for a transmission signal to compensate for the interference amount from the neighboring base station based on the received NI value. Due to such power control, the intensity of a transmission signal of a terminal becomes too strong.
It further degrades the data transmission performance of terminals located at a corresponding base station. In order to overcome such a problem, a Fractional Frequency Reuse (FFR) scheme has been used. In the FFR scheme, a frequency bandwidth is divided for an edge terminal and a central terminal located in a cell of a serving base station. Then, power is controlled by reusing a frequency bandwidth allocated to an edge terminal of a neighboring base station for the central terminal of the serving base station.
Through the above-described power control, the interference to the neighboring cell is reduced. In order to effectively control the interference, the serving base station and the neighboring base station exchange necessary information for the power control through communication.
Further, the serving base station and the neighboring base station transmit the necessary information for the power control to each terminal in order to reduce the power of uplink data that influences terminals located at a service area of the neighboring base station. However, a base station cannot exchange information with a plurality of other base stations when the base station does not establish a communication channel to neighboring base stations because the base station is moving.
Accordingly, it is necessary to minimize interference influencing a service area of a neighboring base station by estimating an interference amount influencing a neighboring cell using a measurement of a signal transmitted from a neighboring base station, and controlling the uplink power for a terminal located at a central area of a corresponding base station based only on the estimated interference.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.